A new study from Columbia University’s Climate School has found that 28 of the most populous cities in the United States are experiencing land subsidence, a phenomenon in which the ground sinks due to natural and human-driven processes. The research, which analyzed over 2,500 satellite radar images between 2015 and 2021, shows that more than one in 10 Americans—an estimated 39 million people—live in cities that are at least partly sinking. The findings, published in Nature Cities, offer the most detailed mapping of urban land movement to date, raising urgent questions about infrastructure vulnerability, flood risk, and climate preparedness in the nation’s largest urban centers.
The 28 cities studied were identified using 2020 U.S. Census data. Together, they include 11 coastal cities, eight riparian cities (those near rivers), and nine inland cities. Nearly half of these cities are also among the fastest-growing in the country. “As cities continue to grow, we will see more cities expand into subsiding regions,” said Leonard Ohenhen, the study’s lead author and a postdoctoral researcher at the Columbia Climate School. “Over time, this subsidence can produce stresses on infrastructure that will go past their safety limit.”
To develop high-resolution vertical land movement maps, researchers created approximately 400 precision images for each city. Unlike previous studies, which looked at broader regions and lacked localized detail, the Columbia analysis was able to pinpoint which specific neighborhoods, roads, and buildings are most at risk. It found that at least two-thirds of the urban area in 25 out of the 28 cities is currently sinking.
The most significant cause of this subsidence is groundwater extraction, accounting for 80 percent of the total sinkage observed. When groundwater is pumped from aquifers, the pressure that supports overlying soil layers is reduced, causing the ground to compact and settle. Other contributing factors include fossil fuel extraction, the sheer weight of buildings and infrastructure, and geological conditions. In cities such as Houston, Texas—identified as the fastest-sinking city in the study—both oil and gas extraction and intensive groundwater pumping are key drivers.
Houston’s statistics are particularly alarming: 42 percent of the city is subsiding faster than 5 millimeters per year, and 12 percent is sinking by more than 10 millimeters annually. In some areas, the land is dropping at rates as high as 5 centimeters (2 inches) per year. Several other Texas cities, including San Antonio, Austin, and Fort Worth, also rank among the most severely affected.
This downward land motion is rarely uniform. Cities such as Jacksonville, Florida; Memphis, Tennessee; and San Jose, California are experiencing differential motion—areas of land sinking or rising at different rates due to variable aquifer levels or human activities. This instability puts enormous stress on infrastructure, increasing the risk of failure in buildings, roads, and pipelines.
“Unlike flood-related subsidence hazards, where risks manifest only when high rates of subsidence lower the land elevation below a critical threshold, subsidence-induced infrastructure damage can occur even with minor changes in land motion,” the study notes. “The latent nature of this risk means that infrastructure can be silently compromised over time, with damage only becoming evident when it is severe or potentially catastrophic.”
The report estimates that one in 45 buildings in San Antonio, one in 71 in Austin, one in 143 in Fort Worth, and one in 167 in Memphis are at high risk of damage due to differential sinking. From 1989 to 2000, at least 225 buildings in the U.S. collapsed; researchers believe only 2 percent were definitively linked to subsidence, but another 30 percent had unknown causes—suggesting that the true number related to ground sinking may be much higher.
The danger is expected to intensify in the coming decades as climate change exacerbates drought conditions, increasing reliance on groundwater. Without stronger management and investment in resilient infrastructure, millions more Americans could see their homes, businesses, and city services threatened by the slow but persistent force of the ground shifting beneath them.
Ohenhen warns that city governments must act decisively. “City planners must acknowledge that land subsidence is not a write-off issue, but a critical amplifier of flood risk and infrastructure vulnerability in cities,” he told Mongabay in an email. He emphasized the importance of incorporating this data into urban planning strategies, including “investments in vulnerable areas, implementing zoning regulations in high-risk zones, and designing infrastructure such as roads, drainage systems, and coastal defenses with projections of future ground elevation changes in mind.”
The Columbia study also offers global context. While urban subsidence is widespread in the U.S., it is far from unique. In California’s Central Valley, excessive groundwater extraction led to land near the California Aqueduct sinking by nearly 28 feet between 1926 and 1970. In recent years, continued pumping during droughts has caused additional declines. And in Mexico City, land is sinking by as much as 20 inches per year—among the highest rates globally.
Ohenhen and his team hope that their findings will be a catalyst for change. Rather than merely identifying the problem, they advocate for proactive solutions. “As opposed to just saying it’s a problem, we can respond, address, mitigate, adapt,” Ohenhen said. “We have to move to solutions.”
That includes building artificial wetlands and other natural drainage systems, updating building codes to account for unstable ground, and retrofitting existing infrastructure with resiliency measures. In rapidly growing cities—particularly those expanding into previously undeveloped areas—ground stability must become a fundamental consideration.
As the climate crisis continues to evolve, the Columbia study serves as a critical warning: the risks facing American cities are not only above ground, but deep below the surface. Addressing these challenges will require a shift in how cities value and manage natural resources, particularly groundwater, and whether they invest in science-informed policies to protect the communities most at risk.
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